Silfab SIL-370-BK 370W vs GAF Energy Timberline Solar ES
The Silfab SIL-370-BK 370W wins this comparison by a decisive margin. It leads in efficiency (20.4% vs 15%) and matches or exceeds on warranty (25 vs 25 years). For most residential installations, the Silfab SIL-370-BK 370W is the stronger choice.
Key Differences
- • Silfab SIL-370-BK 370W is rated at 370W while GAF Energy Timberline Solar ES is rated at 67W, a 303W difference.
- • Silfab SIL-370-BK 370W achieves 20.4% efficiency vs 15% for the other, a 5.4 percentage point gap.
- • Both carry matching 25-year product warranties.
- • Silfab SIL-370-BK 370W has a superior temperature coefficient of -0.35%/°C vs -0.41%/°C, retaining more power in hot climates.
- • Silfab SIL-370-BK 370W uses PERC Mono cells while GAF Energy Timberline Solar ES uses Monocrystalline cells, representing different technology generations.
Specifications Breakdown
Module Efficiency
The Silfab SIL-370-BK 370W achieves 20.4% module efficiency compared to GAF Energy Timberline Solar ES's 15%, meaning Silfab SIL-370-BK 370W converts 5.4 percentage points more sunlight into electricity per square meter. In practical terms, the Silfab SIL-370-BK 370W produces 189.5 watts per square meter of panel area while the GAF Energy Timberline Solar ES produces 148.2 W/m². For rooftop installations where space is limited, this efficiency gap determines how many kilowatts you can fit on your available roof area. Over a 25-year system life, even a small efficiency advantage compounds into meaningful additional energy production.
Power Output
The Silfab SIL-370-BK 370W delivers 370W per panel versus 67W for the GAF Energy Timberline Solar ES, a 303W difference per module. To build an 8 kW residential system, you would need 22 Silfab SIL-370-BK 370W panels or 120 GAF Energy Timberline Solar ES panels. Choosing the higher-wattage option saves 98 panels, reducing total racking hardware, wiring, and installation labor costs. Higher wattage per panel is particularly valuable for commercial-scale installations where panel count directly impacts balance-of-system costs.
Temperature Coefficient
The Silfab SIL-370-BK 370W has a temperature coefficient of -0.35%/°C versus -0.41%/°C for the GAF Energy Timberline Solar ES. On a hot summer day when cell temperature reaches 65°C (40°C above the 25°C STC baseline), the Silfab SIL-370-BK 370W retains 93.0% of its rated power while the other retains 91.8%. This difference is particularly significant in hot climates such as the American Southwest, the Middle East, and Southeast Asia, where panels routinely operate 30-40°C above STC for several hours each day. Over the system lifetime, the cumulative energy advantage from a better temperature coefficient can amount to 2-4% of total production.
Warranty Coverage
The Silfab SIL-370-BK 370W is backed by a 25-year product warranty and 25-year performance guarantee, while the GAF Energy Timberline Solar ES offers 25-year product and 25-year performance coverage. Both offer identical product warranty duration. Based on their published degradation rates (1% first year then 0.4%/year for Silfab SIL-370-BK 370W; 2.5% first year then 0.6%/year for GAF Energy Timberline Solar ES), after 25 years the Silfab SIL-370-BK 370W should retain approximately 89.4% of original output versus 83.1% for the GAF Energy Timberline Solar ES. This 6.3 percentage point gap in end-of-life output meaningfully impacts lifetime energy economics.
Physical Dimensions & Weight
The Silfab SIL-370-BK 370W measures 1722×1134×30mm and weighs 19.5 kg, while the GAF Energy Timberline Solar ES measures 1270×356×10mm at 5.2 kg. 1.95 m² of panel area for the Silfab SIL-370-BK 370W versus 0.45 m² for the GAF Energy Timberline Solar ES. The GAF Energy Timberline Solar ES is 14.3 kg lighter per panel, which reduces structural load requirements on the roof and makes handling easier during installation. For a 20-panel system, that is a total weight difference of 286 kg. The more compact GAF Energy Timberline Solar ES may be easier to fit on irregularly shaped or space-limited rooftops.
Specification Comparison
| Specification | Silfab SIL-370-BK 370W | GAF Energy Timberline Solar ES |
|---|---|---|
| Power | 370W | 67W |
| Efficiency | 20.4% | 15% |
| Power Density | 17.6 W/sq ft | 13.8 W/sq ft |
| Cell Type | PERC Mono | Monocrystalline |
| Bifacial | No | No |
| Weight | 19.5 kg | 5.2 kg |
| Temp Coefficient | -0.35%/°C | -0.41%/°C |
| Snow Load | 2400 Pa | 5400 Pa |
| Wind Load | 2400 Pa | 2400 Pa |
| Product Warranty | 25 years | 25 years |
| Performance Warranty | 25 years | 25 years |
| Degradation (Year 1) | 1% | 2.5% |
| Annual Degradation | 0.4% | 0.6% |
| Country | United States | United States |
5-Dimension Head-to-Head Analysis
1. Efficiency & Power Density
Winner: Silfab SIL-370-BK 370WThe Silfab SIL-370-BK 370W achieves 20.4% efficiency versus 15% — a 5.4 percentage point advantage. On a typical 30-panel residential roof, this translates to approximately 9.1 kW more total system capacity, or 41 kWh more annual production in an average US location.
2. Hot Climate Performance
Winner: Silfab SIL-370-BK 370WThe Silfab SIL-370-BK 370W has a better temperature coefficient of -0.35%/°C versus -0.41%/°C. On a 45°C summer day (20°C above STC), the winner retains 93.0% of rated power versus 91.8%. This is a meaningful difference in hot states like Arizona, Texas, and Florida.
3. Durability & Warranty
Winner: Silfab SIL-370-BK 370WSilfab SIL-370-BK 370W degrades more slowly at 0.4% per year versus 0.6%. After 25 years, expect 89.4% vs 83.1% of original output for Silfab SIL-370-BK 370W and GAF Energy Timberline Solar ES respectively.
4. Power Output
Winner: Silfab SIL-370-BK 370WThe Silfab SIL-370-BK 370W delivers 370W versus 67W per panel — 303W more. For an 8 kW system, you need 22 panels with the higher-wattage option versus 120 panels, saving 98 panels and the associated racking and labor costs.
5. Cell Technology
Winner: GAF Energy Timberline Solar ESThe Silfab SIL-370-BK 370W uses PERC Mono: PERC (Passivated Emitter Rear Cell) is the current mainstream technology, offering good efficiency at the lowest manufacturing cost. The GAF Energy Timberline Solar ES uses Monocrystalline: Monocrystalline. Monocrystalline represents a newer generation technology with a longer performance runway as manufacturing matures.
Silfab SIL-370-BK 370W
The SIL-370-BK is Silfab's entry-level US-made all-black panel delivering 370W for budget-conscious domestic installations.
Pros
- + Made in USA
- + All-black design
- + 25-year warranty
- + ARRA compliant
Cons
- - Lower wattage
- - Basic PERC technology
- - Less competitive efficiency
GAF Energy Timberline Solar ES
The GAF Energy Timberline Solar ES is the world's first nailable solar shingle — installed with a standard nail gun just like conventional roofing shingles. Each 67W unit integrates with GAF Timberline architectural shingles for a low-profile solar roof that any trained roofer can install. Wind rated to 130 mph. Efficiency not publicly disclosed — estimated at ~15%. Installed cost is $4.00-$5.50/W.
Pros
- + World's first nailable solar shingle
- + Installable by standard roofing crews — no solar specialists needed
- + 25-year dual warranty covering power and weatherization
- + 130 mph wind rating — suitable for hurricane zones
- + Class A fire rating
- + Low profile integrates seamlessly with GAF Timberline roofing
Cons
- - $4.00-$5.50/W installed — 2-3x cost of conventional panels
- - ~15% efficiency lower than rack-mounted panels
- - 67W per shingle requires many units for adequate system size
- - Higher operating temperature from flush roof mounting
- - Only available through GAF-certified installers
Choose Silfab SIL-370-BK 370W If...
- ✓ Your roof space is limited and you need maximum power per panel
- ✓ You want fewer panels to reach your target system size, reducing racking and labor costs
- ✓ You live in a hot climate (Arizona, Texas, Florida) where heat performance matters
- ✓ You want maximum output retention over the system's 25-30 year lifespan
- ✓ Government or institutional projects requiring ARRA/Buy America compliance.
Choose GAF Energy Timberline Solar ES If...
- ✓ Homeowners wanting solar that installs like regular roofing, especially during a new roof or re-roof project, with broad installer availability.
Our Recommendation
The Silfab SIL-370-BK 370W is the decisive winner in this solar panel comparison, outperforming the GAF Energy Timberline Solar ES in 4 of 5 dimensions. Unless you have a specific requirement that the GAF Energy Timberline Solar ES uniquely addresses, the Silfab SIL-370-BK 370W is the stronger choice for virtually every installation scenario.
Frequently Asked Questions
Which is better, Silfab SIL-370-BK 370W or GAF Energy Timberline Solar ES?
The Silfab SIL-370-BK 370W wins this comparison by a decisive margin. It leads in efficiency (20.4% vs 15%) and matches or exceeds on warranty (25 vs 25 years). For most residential installations, the Silfab SIL-370-BK 370W is the stronger choice.
Which panel is more efficient, Silfab SIL-370-BK 370W or GAF Energy Timberline Solar ES?
The Silfab SIL-370-BK 370W at 20.4% module efficiency. Higher efficiency means more watts per square foot of roof space, which is critical for space-constrained installations. The difference of 5.4 percentage points translates to approximately 303W per panel under standard test conditions.
Which has a better warranty, Silfab SIL-370-BK 370W or GAF Energy Timberline Solar ES?
The Silfab SIL-370-BK 370W comes with a 25-year product warranty and 25-year performance guarantee. The GAF Energy Timberline Solar ES offers 25-year product and 25-year performance warranties. Both offer identical warranty terms.
Which panel performs better in hot weather?
The Silfab SIL-370-BK 370W has a temperature coefficient of -0.35%/°C and the GAF Energy Timberline Solar ES is -0.41%/°C. Silfab SIL-370-BK 370W retains more power in heat — important in states like Arizona, Texas, and Florida. A lower (less negative) temperature coefficient is better.
How many Silfab SIL-370-BK 370W vs GAF Energy Timberline Solar ES panels do I need for an 8 kW system?
For an 8 kW system: you need 22 Silfab SIL-370-BK 370W panels (370W each) or 120 GAF Energy Timberline Solar ES panels (67W each). The Silfab SIL-370-BK 370W requires fewer panels, saving on racking hardware and installation labor.
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Last updated: February 2026